1. Field of the Invention
This invention relates to plastic composite bottles and, more particularly, to polyethylene terephthalate (PET) bottles comprising a container portion and a base portion, the base portion being formed with an upwardly extending annular saddle to contact and support a spherical lower end of the container portion and with the two portions being welded together at the saddle. This invention also relates to the method of, and apparatus for, welding together such portions.
2. Description of the Background Art
Various types of plastic bottles manufactured from synthetic resins are in wide use throughout the carbonated beverage industry, principally because of their economical cost of manufacture. Such plastic bottles are usually formed from injection molded parisons with an elongated container portion. The parisons are blow-molded to their intended size and shape by positioning them in a blow-molding unit, applying heat, and then injecting air to thereby blow-mold them into the desired shape.
Experience has shown that the blow-molding of bottles with flat bottoms is not satisfactory in terms of stability in remaining vertically erect while at rest and in terms of durability against deformation during use. Consequently, virtually all blow-molded parisons include rounded bottoms to which is attached an injection-molded base cup portion to form a composite bottle. The base cup portion provides great stability and durability to the bottle.
The background art discloses many types of composite bottles as well as many methods and apparatus for welding their upper container portions with their lower base cup portions. Consider, for example, U.S. Pat. No. 4,609,418 to Yoshino. According to that patent, an upper container portion with a spherical lower end is attached to a lower base cup portion. The lower base cup portion has an upstanding saddle for contacting and supporting the spherical lower end portion of the container portion. An adhesive is applied between the container portion and the base cup portion at the saddle area. The use of adhesives, however, increases the cost of the resulting composite plastic bottle since an additional element, the glue, has been added. The use of glue also constitutes an added element of inconvenience to the fabrication method and machinery. Further, the addition of glue complicates the ability to recycle such plastic bottles after their use. It has been an increasing practice to recycle used plastic bottles and to fabricate new bottles from such materials. If a foreign substance such as the glue is part of the recycled material, an additional step must be added to the recycling process in order to remove such glue. Such complication thereby adds to the time and cost of the recycling which increases the cost of the resulting recycled bottle.
Also disclosed in the background art is the welding together of upper container portions and the lower base cup portions to form composite bottles. Note, for example, U.S. Pat. No. 4,331,246 to Sorensen and Canadian Patent No., 124,470 to Jakobsen. According to such disclosures, the coupling of the container and base cup portions is effected by a weld, such weld being effected at a central point of contact therebetween. The weldment is thus a single spot of variable size along the vertical central axis of the bottle, container portion and base cup portion. As a result, the size and nature of the welded portion, as well as the strength of attachment between the welded portions, will create problems of consistency in the resulting composite bottle. Further, during the fabrication process, when a circular welding element contacts a single central area of the base cup portion, the support is at such central area only thereby providing minimum stability and support for the base cup. This thereby tends to result in inferiorly joined composite plastic bottles.
Typical continuous and automatic machinery for fabricating composite plastic bottles is disclosed in U.S. Pat. No. 4,132,584 to Aidlin and in U.S. patent application Ser. No. 06/931,178 filed Dec. 10, 1986 in the name of Aidlin and assigned to the assignee of the instant invention, now U.S. Pat. No. 4,765,119. Such typical machinery with their attendant methods, do not disclose, teach or suggest the welding of the spherical lower end of containers with the raised saddle portions of base cup portions for the fabrication of superiorly joined bottle portions and, thereby, superior composite bottles.
None of this background art discloses or teaches or suggests a composite plastic bottle characterized by an efficiently joined base cup portion and container portion as herein disclosed and claimed. Further, there is no known background art which discloses or teaches or suggests a method of, or apparatus for, the efficient, convenient, accurate and economic fabricating of composite plastic bottles with annular weldments as described and claimed herein. The methods, apparatus and bottles of the background art are simply lacking in one regard or another.
As illustrated by the large number of background patents and known commercial techniques, efforts are continuously being made in an attempt to improve composite plastic bottles and to manufacture them more efficiently, conveniently, reliably and economically. None of these previous efforts, however, provides the benefits attendant with the present invention. Additionally, prior techniques do not disclose, teach or suggest the present inventive combination of component elements and method steps as disclosed and claimed herein. The present invention achieves its intended purposes, objectives and advantages over the prior art devices through a new, useful and unobvious combination of component elements which is simple to use, with the utilization of a minimum number of functioning parts, at a reasonable cost to manufacture and use and by employing only readily available components.
Therefore, it is an object of this invention to provide an improved plastic bottle formed of a container and a base cup for receiving one end of the container, the base cup having an annular area for contacting and supporting the recessed end of the container, the container and the base cup being welded together at the annular area.
It is a further object of the invention to provide apparatus for joining together a lower base cup component and upper container component of a composite bottle by an annular weldment.
Lastly, it is a further object of the invention to weld together the container and base cup portions of a composite plastic bottle at the saddle area of the base cup.
The foregoing has outlined some of the more pertinent objects of the invention. These objects should be construed to be merely illustrative of some of the more prominent features and applications of the intended invention. Many other beneficial results can be attained by applying the disclosed invention in a different manner or modifying the invention within the scope of the disclosure. Accordingly, other objects and a fuller understanding of the invention may be had by referring to the summary of the invention and the detailed description of the preferred embodiment in addition to the scope of the invention defined by the claims taken in conjunction with the accompanying drawings.